It's a tough enough job protecting your home computer, or your business network, against the rising threat of malware and determined hackers... imagine if you were responsible for the security of Britain's nuclear deterrent?

It's one of the creepiest things you can experience on Facebook. You stumble across the profile of "another" user who appears to have stolen the details of your life - lock, stock and barrel. And they are spreading slurs about your character, and befriending your contacts...